Research has discovered that port-injected fuel that wets wall surfaces leading to a cylinder intake can make a detrimental contribution to undesired tailpipe emissions. Because of increasingly strict regulation of tail pipe emissions, it has become increasingly important that such wall wetting be minimized to the greatest degree possible, and ideally eliminated entirely. A common construction of a mounting socket for an electrically operated gasoline fuel injector that injects fuel into a runner leading to a cylinder's intake comprises an antechamber immediately adjoining the socket's intersection with the runner. In a typical fuel injector, an O-ring seal is present near the injector tip. Certain constraints or considerations, such as for example, 1) the need for sufficiently strong wall structure at the location where the injector mounting socket intersects the runner, 2) packaging constraints that are imposed on the underhood mounting of the engine in an automotive vehicle, 3) the size and shape of a runner, and/or 4) the particular fuel injector to be used, will typically dictate the disposition of a fuel injector mounting socket in relation to its associated runner. The resulting designs have heretofore disposed the tip, or nozzle, of the fuel injector in the antechamber and the injector is constructed to deliver the injected fuel toward a target zone, typically a cylinder intake valve. Such delivery may take different forms such as a bent stream, i.e. a stream that is non-parallel to the axis of the injector, or a straight stream, i.e. one that is co-axial with the co-axis of the fuel injector and its mounting socket. Several examples of port-injection are shown in U.S. Pat. Nos. 5,085,369; 5,156,130; and 5,201,806.
It has now been discovered that the presence of the injection point within the antechamber can give rise to some small, but nonetheless significant insofar as tail pipe emissions are concerned, amount of recirculation of injected fuel that tends to promote wall wetting to the detriment of tail pipe emissions. It may be generally said that the present invention relates to a new and unique organization and arrangement for a gasoline port fuel injector that can accommodate constraints and considerations such as those mentioned above, yet also reduces or eliminates the aforementioned recirculation problem.
Briefly the invention comprises: an internal combustion, spark-ignition engine comprising an intake runner through which air is inducted into an engine cylinder and an electrically operated fuel injector disposed coaxially within a fuel injector mounting socket that intersects the runner, said mounting socket comprising an antechamber immediately adjoining the socket's intersection with the runner, an O-ring seal disposed to seal a circumference of said fuel injector to said socket at a location that leaves at least some of said antechamber unsealed from said runner, said fuel injector comprising a nozzle from which fuel is injected into said runner for entrainment with air passing through said runner in a direction toward an intake of said engine cylinder, said fuel injector nozzle comprises orifice means at which the injected fuel exits the fuel injector, characterized in that said orifice means is disposed beyond said antechamber so as to lie within said runner and inject the fuel from a location that does not lie within said antechamber.
The invention is disclosed in an embodiment further characterized in that said fuel injector's orifice means are in a disk that is disposed transversely within a body portion of said nozzle leaving said body portion with a rim disposed just beyond said disk, and the entirety of said rim is disposed beyond said antechamber so as to lie within said runner.
The disclosed embodiment of the invention is still further characterized in that said orifice means is disposed substantially on the axis of the fuel injector, and the fuel is injected in a direction that is non-parallel to the co-axis of the fuel injector and its mounting socket.
Principles of the invention may be incorporated into embodiments other than the one specifically illustrated in the accompanying drawing, such as one in which the injector stream or spray is parallel with the co-axis of the injector and its mounting socket.
Features, advantages, and benefits of the invention will be seen in that drawing as well as in accompanying description and claims disclosing a presently preferred embodiment according to the best mode contemplated at this time for carrying out the invention.